Electric water heater

ABSTRACT

In accordance with this invention there is provided an electric water heater and storage tank wherein only a single electric heating element is vertically mounted near the bottom of the tank and is surrounded by a spaced-apart tube which is a good thermal insulator, such as a plastic tube. The insulator tube is open at the bottom for cold water inlet and has openings at the top for hot water outlet near the middle of the tank, forming a circulating system within the tank to cause cooler water to sweep across the surface of the electric heating element for economy and to greatly reduce stratification of the hot water within the tank.

United States Patent [72] Inventor Gordon H. I-Iepplewhite 3940Ellendale Road, Moreland Hills, Ohio 44022 [21] Appl. No. 1,788 [22]Filed Jan. 9,1970 [45] Patented Oct.19,197 1 [54] ELECTRIC WATER HEATER2 Claims, 1 Drawing Fig.

[52] US. Cl 219/312, 219/314,219/316 [51] Int. Cl F24h 1/20 [50] Fieldof Search 219/310, 312, 314,315, 316, 318

[56] References Cited UNITED STATES PATENTS 1,082,168 12/1913 Philpetal219/315 1,470,834 10/1923 Hasse1bach.. 219/314 X 1,950,113 3/1934Kirkwood.... 219/316 X 2,636,974 4/1953 Bowen 219/314 Primary ExaminerJ.V. Truhe Assistant ExaminerC. L. Albritton Attorney-Ebcr .1. HydeABSTRACT: In accordance with this invention there is provided anelectric water heater and storage tank wherein only a single electricheating element is vertically mounted near the bottom of the tank and issurrounded by a spaced-apart tube which is a good thermal insulator,such as a plastic tube. The insulator tube is open at the bottom forcold water inlet and has openings at the top for hot water outlet nearthe middle of the tank, forming a circulating system within the tank tocause cooler water to sweep across the surface of the electric heatingelement for economy and to greatly reduce stratification ofthe hot waterwithin the tank.

unin- ELECTRIC WATER HEATER BACKGROUND OF THE INVENTION In the past,electric water heaters have used multiple heater elements in conjunctionwith multiple thermostats to rapidly heat water in storage tanks. Whenthe demand for hot water was great both heater elements were energized,and when demand was less only one element, usually the lower one, wasenergized. The heater elements were inserted horizontally into thestorage tank, necessitating more plumbing fixtures for the tank withconsequent increased cost, and requiring increased cost for the heaterelements, thermostats and wiring. Also, because the upper element wasenergized less of the time and was positioned in the area of the hotwater, increased burn-out of the lower element took place. Thetwo-heater element, horizontal mounting caused stratification of the hotwater.

It is an object of the present invention to provide an electricwaterheater and storage tank system which is less expensive tomanufacture, less expensive to operate, and less expensive to maintain.

It is another object of the invention to provide an electric waterheater and storage tank system wherein only a single heater element isused, the element being vertically mounted and shielded in such a manneras to increase circulation of the water being heated, thereby to greatlyreduce stratification of the water within the tank.

Another object of the invention is to provide an electric water heaterand storage tank system wherein a single, vertically mounted heaterelement promotes circulation of cooler water past its surface, therebyto more efficiently transfer heat from the element to the water withconsequent longer element life, better water circulation within thestorage tank, and reduced consumption of electric current for amount ofheated water delivered.

Still another object of the invention is to provide an electric waterheater and storage tank system which is easier to service due to only asingle heater element being used, and due to only a single thermostatbeing employed.

Still a further object of the invention is to provide an electric waterheater and storage tank wherein less electricity is consumed to heat agiven amount of water to a fixed temperature, thereby reducing theamount of scale which is formed, in the tank with consequent reducedcorrosion.

It is also an object of the invention to provide a system wherein thecirculation within the tank due to the electric element heating thewater is enhanced by the circulation set up by the use of hot water andthe flow of incoming cold water.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointed out in the appended claims.

With reference to the drawing the FIGURE showsa crosssectional view of awater heater and storage tank utilizing electric current as the energysource.

Reference character indicated a metal water storage tank having aninsulator 11 (only partly shown) around its outside surface, and with anoutside cover 12 around the insulation, as is known in the art. A coldwater inlet pipe 13 extends downwardly through the top 15 of the tank toa location near the bottom 16 of the tank, and a hot water outlet pipe17 extends through the top 15 and into the tank only a short distance sothat it draws water out of the tank only from near the top where thewater is hottest.

A plastic dry well tube or a plastic-covered metal tube 20 extends downthrough the top 15 of the tank to a location very near, but spaced from,the bottom 16. The dry well tube 20 includes a short metal pipe 19 whichis secured to the top of the tank 10 by a threaded section 21, and it isenclosed by cover 22 which has one or more holes 23 through which wiresextend. The dry well tube 20 is secured to the short metal pipe 19 by arolled connection 25, or other such connection, which is leak-proof toprevent water from entering the dry well 20.

The dry well 20 extends down into the storage tank approximately halfthe height of the tank, where it terminates in a heating element adapter26. The heating element adapter 26 is small enough that it will passthrough the opening at the top of the tank when the metal pipe 19 isunscrewed therefrom, thereby facilitating the exchange of a new heatingelement for an old one if service becomes necessary. Wires 27,28 from anoutside source of electric current are connected to terminals 29,30mounted on the heating element adapter 26, and of course may be enclosedin a manner to prevent water from contacting them in the event of a leakin the dry well pipe 20.

Extending downwardly from the heating element adapter 26, and connectedto it by suitable means such as one or more set screws 32 is a plastictube 35 which is open at its bottom end 36, and which has a plurality ofopenings 37 at its top end. The plastic pipe 35 surrounds and is spacedfrom a single, vertically mounted, electric heating element 40 which issecured to the adapter 26 by suitable means, not shown. The heatingelement 40 is electrically connected to the wires 27,28 for energizationthereby, and a thermostat 41 is mounted through the wall of the tank 10and by switch 42 controls the energization of the single heating element40, as is known in the art. Alternatively, the thermostat may be surfacemounted on the outside of the tank.

Assume that the tank 10 is full of cold water. The inside of the drywell 20 is devoid of water, and water fills the space between the heaterelement 40 and the plastic tube 35. The thermostat 41 calls for heatcausing switch 42 to close, thereby energizing the heater element 40. Asthe very limited quantity of water within tube 35 is quickly heated itrises and flows out of the openings 37 at the top of the tube, and isreplaced by cooler water flowing in at the opening 36 at the bottom. Theheated water rises as is shown by arrows 50 displacing cooler watertoward the bottom of the tank as shown by'arrows 51. Thus, circulationof water is quickly established and is maintained within the tank, hotwater rising to the top and cooler water falling toward the bottom. Thiscirculation greatly reduces stratification of the water in the tank intohotter and cooler regions as is usual in conventional tanks of thehorizontally mounted two-element type.

When hot water is withdrawn from tank 10 through pipe 17 it is replacedby cold water through pipe 13 whose outlet is near the bottom 16 of thetank. Thus no cold water enters at a location where it can mix directlywith hot water at the top of the tank, and the circulation of waterwithin the tank is aided by the flow of hot water out and cold waterinto the tank.

Because of the plastic tube 35 around, but spaced from, the heatingelement 40 there is a continuous and generous flow of water up the tube35 at all times while the element 40 is energized. This maintains theelement at a somewhat lower temperature due to the flow of cooler bottomwater across its surface, leading to longer element life for severalreasons; the lower operating temperature of the element, less scale onthe element, less corrosion, and less electrolysis due to the shieldingeffect of the plastic pipe.

While there has been described what is at present considered to bethepreferred embodiment of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

What is claimed and desired to be secured by United States LettersPatent is:

1. An electric water heater and storage tank system comprising, incombination; a vertical-type storage tank having an opening at its top,means for connecting a hot water withdrawal pipe into the tank near thetop thereof, means for connecting a cold water inlet pipe through thewall of the tank, the inlet pipe terminating near the bottom of thetank, a dry well mounted through the opening at the top of the tank andextending into the tank, only a single elongated electric heatingelement connected to said dry well and extending vertically into saidtank for engagement with water therein, electric wiring means connectedto said heating element and extending into said dry well and out of thetank at said opening at the top of the tank, heat-insulating pipe meansconnected to said dry well and surrounding but spaced from said heatingelement, said insulating pipe being open at its bottom end and having anopening at its top end where it is connected to said dry well for flowof water therethrough and in contact with the said heating element, andthermostatic means mounted on said tank and connected electrically withsaid electric wiring means for controlling the energization of saidheating element.

2. An electric water heater and storage tank comprising, in combination:a vertical-type storage tank having an opening at its top, means forconnecting a hot water withdrawal pipe near the top of the tank, meansfor connecting a cold water inlet pipe through the wall of the tank, theinlet pipe terminating near the bottom of the tank, a dry well throughthe said opening at the top of the tank and extending into the tank to alocation about the middle of the tank, a heating element adapterconnected to the bottom of the dry well, an elongated electric heatingelement connected electrically and mechanically to said adapter andholding said element vertically within said tank, heat-insulating pipemeans connected to said dry well and surrounding but spaced from saidheater element, said pipe means having openings at its top and having anopen bottom near the bottom of the tank, electric wires extending fromthe outside of said tank down through said dry well to said adapter andto said heating element, and thermostat means mounted on said tank andconnected to said electric wires for sensing the temperature of thewater therein and for controlling the energization of said heaterelement.

1. An electric water heater and storage tank system comprising, incombination; a vertical-type storage tank having an opening at its top,means for connecting a hot water withdrawal pipe into the tank near thetop thereof, means for connecting a cold water inlet pipe through thewall of the tank, the inlet pipe terminating near the bottom of thetank, a dry well mounted through the opening at the top of the tank andextending into the tank, only a single elongated electric heatingelement connected to said dry well and extending vertically into saidtank for engagement with water therein, electric wiring means connectedto said heating element and extending into said dry well and out of thetank at said opening at the top of the tank, heat-insulating pipe meansconnected to said dry well and surrounding but spaced from said heatingelement, said insulating pipe being open at its bottom end and having anopening at its top end where it is connected to said dry well for flowof water therethrough and in contact with the said heating element, andthermostatic means mounted on said tank and connected electrically withsaid electric wiring means for controlling the energization of saidheating element.
 2. An electric water heater and storage tankcomprising, in combination: a vertical-type storage tank having anopening at its top, means for connecting a hot water withdrawal pipenear the top of the tank, means for connecting a cold water inlet pipethrough the wall of the tank, the inlet pipe terminating near the bottomof the tank, a dry well through the said opening at the top of the tankand extending into the tank to a location about the middle of the tank,a heating element adapter connected to the bottom of the dry well, anelongated electric heating element connected electrically andmechanically to said adapter and holding said element vertically withinsaid tank, heat-insulating pipe means connected to said dry well andsurrounding but spaced from said heater element, said pipe means havingopenings at its top and having an open bottom near the bottom of thetank, electric wires extending from the outside of said tank downthrough said dry well to said adapter and to said heating element, andthermostat means mounted on said tank and connected to said electricwires for sensing the temperature of the water therein and forcontrolling the energization of said heater element.